On Jan. 1, 1991 the United States Government adopted and put into effect The United Nation's Chapter 9 Recommendations for the Transport of Dangerous Goods. This action mandates changes in the heretofore accepted Department of Transportation Regulations for Hazardous Goods.
The change set forth in the United Nations Chapter 9 Recommendations altered the test height from which a container is dropped in determining the sealing integrity of the dropped container. The "drop test" previously required a container to be dropped forty eight inches whereas the United Nation's Recommendations requires the container to be dropped ninety inches. A "hydrostatic test" is also required by the United Nations Recommendations whereby containers must withstand an internal hydrostatic pressure of 37 PSI without leaking.
A container commonly subjected to this test and most widely used for the transportation of generally classified hazardous materials is a cylindrical bucket having a circular bottom a substantially cylindrical outer wall and a circular cover panel. The cover panel extends over a rim defining the upper margin of the bucket and is secured thereto by relatively rigid but malleable tabs that extend beneath the rim and against the outer wall. A securing ring, commonly referred to as a lever latch ring, circumscribes the rim outwardly thereof and is drawn in pressed engagement therewith to press an outermost portion of the cover panel in pressed abutment with the rim. The ring is defined by an arcuate, cross-sectionally C-shaped member substantially forming a circle and a lever latch connected to adjacent opposing ends of the arcuate member for drawing the ends together and thus the arcuate member inwardly toward the rim. The C-shaped, arcuate member is formed by a vertical portion circumscribing the rim and drawn into contact with the outermost portion of the cover panel, an upper horizontal portion extending from an upper margin of the vertical portion above the rim and a lower horizontal portion extending from a lower margin of the vertical portion below the rim. The upper and lower horizontal portions secure the vertical portion proximal the rim but do not exert any pressure on the cover panel or the tabs forming a portion thereof. The securing pressure provided by such lever latch rings is applied only at the outermost point of the cover panel and rim. The lower horizontal portion is actually spaced from the tabs and outer wall.
Though the lever latch ring set forth above has been used for years, it cannot prevent leakage when a hydrostatic pressure of thirty seven PSI is introduced within the container. In fact, it is difficult if not impossible for the aforesaid lever latch ring to sustain a hydrostatic pressure of twenty PSI without experiencing leakage. Obviously such lever latch rings and associated containers will not meet the Department of Transportation's new requirements for hazardous waste materials thus an improved container and lid engaging and sealing apparatus is required.